2A Symmetry

Question 1

An operation performed on an object which leaves it in a configuration that is indistinguishable from and superimposable on the original configuration

Answer 1

Symmetry operation

Question 2

A symmetry operation is carried out with respect to

Answer 2

Points or lines or planes

Question 3

Operation or element: rotate by 360/n

Answer 3

Operation

Question 4

Operation or element: n fold axis

Answer 4

Element

Question 5

Operation or element: reflection

Answer 5

Operation

Question 6

Operation or element: mirror plane

Answer 6

Element

Question 7

Operation or element: inversion through a center

Answer 7

Operation

Question 8

Operation or element: point

Answer 8

Element

Question 9

Operation or element: improper rotation

Answer 9

Operation

Question 10

Operation or element: n fold axis and a mirror plane

Answer 10

Element

Question 11

Molecule notation by

Answer 11

Schoenflies

Question 12

Crystal notation by

Answer 12

Hermann-Mauguin

Question 13

Symbol E

Answer 13

Identity

Question 14

Symbol Cn

Answer 14

Rotation by 360/n; n fold symmetry axis

Question 15

Symbol σ

Answer 15

Reflection, mirror plane

Question 16

Symbol i

Answer 16

Inversion

Question 17

Symbol Sn

Answer 17

Rotation followed by reflection in plane perpendicular to rotation axis; n fold axis of improper rotation

Question 18

Properties of a group

Answer 18

Must have identity that commutes but leaves them unchanged (EA=AE=A). Must have inverse that yields the identity. Product of any two members must also be a member of the group. Associative property must hold A(BC)=(AB)C.

Question 19

C1 symmetry

Answer 19

None other than identity operation

Question 20

Cs symmetry

Answer 20

One mirror plane

Question 21

Ci symmetry

Answer 21

Only inversion center